Schizophrenic patients have consistent difficulty focusing attention for specific tasks. Knowledge of the mechanism(s) of attentional impairment may provide important information about the pathophysiology of schizophrenia, since attentional impairment may mark vulnerability or trait characteristics of the illness. Deficits in attention may occur because of localized abnormalities in central regions or systems which allocate selective attention, e.g. prefrontal cortex, or because of more widespread abnormalities, e.g. from a failure of cortical ontogenesis, which could affect the earliest levels of sensory processing. We will test the general hypothesis that simple sensory processing is abnormal in schizophrenia, a prediction derived from evidence suggesting widespread sturctural abnormalities in the cortex of schizophrenic brains. Proposed experiments will test specific formulations of this hypothesis to better characterize the dysfunction, mainly in visual cortex, and to elucidate how it may contribute to abnormal attention in schizophrenia.